Patent GB-449995-A (GB)
Title: Improvements in and relating to electric power switches
IPC: H01H33/12
Filed: 1935-11-09
Abstract: 449,995. High - tension switches; arc - rupturing in switches. SIEMENSSCHUCKERTWERKE AKT.-GES., Siemonsstadt, Berlin. Nov. 9, 1935, Nos. 31069 and 31070. Convention dates, Nov. 10, 1934 and Nov. 17, 1934. [Class 38 (v)J Actuating.-A power switch has two points of interruption and a positive driving connection between the switch driving gear and the two sets of contacts so that the latter are operated in common but with switching movements separated in time. A positive connection between the movable contacts is ensured during the entire switching operation, both in switching in and in switching out, and the former function is allocated to one set of contacts and the latter function to the other set. The movable contact rod 7 co-operating with the fixed contact 6 in chamber 3a, is guided on rods 14, 15 which, with connector 16, serve serially to connect it with the supplementary movable contact 9 pivoted at A. An insulating operating rod 17 driven by compressed-air or a spring, acts on a lever S which is linked at 13 to the rod 7 and is mounted on a shaft H carrying a cam plate F. An extension T of the contact 9 carries a roller 27 working in a continuous groove 21, 22 in the plate F. In opening the circuit, lever S and plate F are rotated anticlockwise to effect a break at 6, 7, but as the roller 27 moves at first along a part of the groove 21 which is concentric with axis H, no movement of 9 occurs. When 27 encounters the cam part of groove 21 the arm 9 is swung to open position and a spring-pawl 23 engages behind the roller 27 to prevent the latter moving back along the groove 21 in closing circuit. In the latter operation, a concentric part of groove 22 causes the arm 9 to stay open until the pin 7 has nearly reached its closed position, whereupon the cam part of groove 22 moves 9 to closed position. A spring-pawl 24 engages behind the roller 27 and not only prevents its moving back along groove 22. but even forces it to complete the closing movement, so proventing arcing at 9, 10 supposing the switch is immediately reopened by a short-circuit. In Fig. 2, the grooves 30, 31 are provided with extensions 32, 33 and the guided element 34, pivoted at 35, is elongated so that tho element is constrained to follow the path indicated by the arrows. In Fig. 3, 37 is the guided break contact and 38 the guided make contact, the two being electrically and pivotally connected to strip 44, which is pivoted at 45 to an arm 46 on a spindle H driven by a shaft 36, which is rotated anticlockwise to operate the switch on and off. In moving from the on position (shown in full lines), anticlockwise rotation of 46 causes 44 to rotate clockwise about 45 so moving 38 farther through contacts 40 and raising 37 from contacts 39 located in an expansion or blast chamber. On continued rotation, of 46. the rod 38 is moved clear of contacts 40 and the switch is fulty opened, as shown in dotted lines. To reclose, 46 is again rotated anticlockwise and first closes 37, 39 and then 38, 40. In the modification shown in Figs. 5, 9, 11, the supplementary arm 109 is pivoted at A and has an extension T in which is pivoted a roller 142, Fig. 9, bearing on the edge of the cam plate F. The latter is free on shaft H carrying the levers S, S<1>, S<2> which are coupled for joint movement to actuate the main movable contact. Normally a torsion spring 133 with arms 134, 135 co-operating with pins 136 .. 139, the last-named being on the lever S<2> while the others are on the plate F, constrains the latter to move with the shaft H, but a certain amount of relative movement is allowed to ensure completion of the movement of 109 with a snap action. Levers S<1>, S<2> are provided with rollers 140, 141 respectively co-operating with grooves 144, 145 on the front and back of lever T. To close from the Fig. 11 position, S, S<1>, S<2> Hare rotated clockwise, carrying with them the plate F, the concentric surface 148 of which engages the roller 142 of lever T to prevent closure thereof until that roller reaches the inclined end 149. At this point, corresponding with the nearly-closed position of the main switch, roller 141 engages the surface of groove 145 and rotates lever T and contact 109, the roller 142 then engaging the oblique surface 149 to drive the latter clockwise and stress the spring 133, Fig. 9. When the parts have crossed the dead-centre line A, H, the backward thrust of spring 133 and plate F on roller 142 causes the latter to drive the part T, 109 to the fully-closed position, the roller 142 again riding up the surface 149, Fig. 5, to lock the parts closed even if the lever arms S, &c. move in the opening direction. Once the roller 141 has, in the latter part of the closing movement, passed the point 156 between the surfaces 147, 157, any backward movement of S<1> to the left, due to the lever arms moving in the opening direction, sets up a pressure in the closing direction of the contact 109.